In the past decade, as electronic devices such as notebook computers, personal digital assistants (PDAs), portable navigation device (PNDs), media players, mobile phones, portable inventory devices (PIDs) . . . etc. (frequently referred to as “portable computing devices”) have converged while at the same time becoming small, light, and functionally more powerful. One factor contributing to the development and availability of such smaller devices is an ability to increase computational density and operating speed by ever decreasing electronic component sizes. However, the trend to smaller, lighter, and functionally more powerful electronic devices presents a continuing challenge regarding design of some components of the portable computing devices.
Components associated with the portable computing devices encountering particular design challenges include the enclosure or housing used to house the various internal/electronic components. This design challenge generally arises from two conflicting design goals—the desirability of making the enclosure or housing lighter and thinner, and the desirability of making the enclosure or housing stronger and more rigid. Lighter enclosures or housings, typically thin plastic structures with few fasteners, tend to be more flexible while having a tendency to buckle and bow as opposed to stronger and more rigid enclosure or housings, typically thicker plastic structures with more fasteners having more weight. Unfortunately, the increased weight of the stronger, more rigid plastic structures might lead to user dissatisfaction, while the bowing and buckling of the lighter structures might damage the internal/electronic components of the portable computing devices and almost certainly leading to user dissatisfaction.
Among known classes of materials are glass-ceramics that are used widely in various other applications. For example, glass-ceramics are used widely in kitchens as cooktops, cookware, and eating utensils, such as bowls, dinner plates, and the like. Transparent glass-ceramics are used in the production of oven and/or furnace windows, optical elements, mirror substrates, and the like. Glass-ceramics are typically made by ceramming precursor glass compositions at specified temperatures for specified periods of time to nucleate and grow crystalline phases in a glass matrix. Two glass-ceramics based on the SiO2—Al2O3—Li2O glass system comprise those having either β-quartz solid solution (β-quartz ss) as the predominant crystalline phase or β-spodumene solid solution (β-spodumene ss) as the predominant crystalline phase. There exists a need for colorable and ceramable glasses and/or colored and opaque glass-ceramics and/or ion exchangeable colored and opaque glass-ceramics and/or ion exchanged colored and opaque glass-ceramic that provide improved black or grey colors for enclosures or housings of portable computing devices. Also, there exists a need for such materials that provide such improved colors while addressing the design challenge of creating light, strong, and rigid enclosures or housings.